Many rockets and missiles include one or more solid rocket motors to generate thrust to achieve and/or maintain flight, and/or to control in-flight direction. A solid rocket motor may include, for example, a motor case and a main nozzle. Typically, the motor case defines a combustion chamber, in which propellant is loaded and combusted to generate high-energy propellant gas. The main nozzle is typically in fluid communication with the combustion chamber and thus receives the high-energy propellant gas. The main nozzle may include a convergent inlet section, a divergent outlet section, and an interposing main nozzle throat. Propellant gas generated in the combustion chamber flows through the main nozzle, generating a thrust.
Solid rocket motors, such as the one briefly described above, are used in both strategic and tactical rockets and missiles. In general, strategic missiles are used for long duration missions, whereas tactical missiles are used for relatively short duration flight missions. Both types of missiles may be equipped with guidance control systems, which in many instances use attitude control valves to selectively divert a portion of the high-energy propellant gas away from the main nozzle to one or more peripheral nozzles, to thereby control missile attitude.
The attitude control valves that are used in guidance control systems, such as that described above, may be exposed to relatively high temperatures. For example, in some applications the propellant gas flowing through the valves may reach temperatures of up to 5,000° F. or higher. Thus, the attitude control valves in some missile and rocket applications, and most notably for strategic missiles and rockets, are constructed of relatively high-temperature materials, such as refractory metals.
Although attitude control valves constructed of high-temperature materials, such as refractory metals, operate safely, reliably, and robustly, these valves do exhibit certain drawbacks. For example, in most current applications the relatively high-temperature propellant gas flows into and through the control valves and exerts a tensile force on the valve. To assure the valve maintains sufficient material strength throughout the mission, the thickness of various portions of the valve may need to be increased. However, in many instances the high-temperature materials used to construct the attitude control valves often have relatively high densities. As a result, increasing the thickness of various portions of the valves can significantly increase the weight of the valve, and thus the overall weight of the rocket or missile, which can be highly undesirable.
Hence, there is a need for a valve that can withstand relatively high temperatures over a relatively long time period, without adversely impacting the weight of the system in which the valve is installed. The present invention addresses at least this need.